Microfluidic systems have been previously described for carrying out a number of operations, including, e.g., capillary electrophoresis (Manz et al., J. Chromatog. 593:253-258 (1992)), gas chromatography (Manz et al., Adv. In Chromatog. 33:1-66 (1993)), cell separations (U.S. Pat. No. 5,635,358) and the like. Generally, such devices have been described in the context of proof-of-concept experiments, where they have been used in operations primarily performed by highly skilled technicians. Despite the advancements made with respect to these devices, however, such devices have not been adapted for use by less sophisticated operators.
In particular, the microfluidic devices and systems for controlling and monitoring the devices described to date, have generally included bulky, complex and expensive prototypical systems whose use requires complex series of operations and or a high level of skill on the part of the operator. Further, such systems are generally fabricated in the lab, where time and funding can be at a premium, resulting in little or no attention being given to features of the device that are not specifically directed to the fluidic elements. As such, these devices tend to be extremely sensitive to operator handling, and by implication, operator error. It would therefor be desirable to provide microfluidic devices and/or systems which are more xe2x80x9cuser friendly,xe2x80x9d i.e., more resistant to operator error, and particularly, operator handling error. The present invention meets these and other needs.
The present invention generally provides improved microfluidic devices, apparatus and systems which reduce the potential for errors which arise from operator mishandling of such devices. In particular, the present invention provides microfluidic devices which comprises a substrate having a first surface and at least one edge, at least two intersecting microscale channels disposed in the substrate, and a detection window in the first surface which permits transmission of an optical signal from at least one of the at least two intersecting channels. These devices also comprise a manual handling structure attached to the substrate for handling the microfluidic device substantially without contacting the first surface of the substrate. Also provided are apparatus for utilizing these devices, which apparatus include electrical control systems for applying an electric field across each of the at least first and second intersecting channels within the device, as well as optical detectors disposed adjacent to the detection window within the device for receiving the optical signal.